Claude Opus 5.5 vs MiniMax M3.1 Flash

Claude Opus 5.5
$1.34 / task
Wins 4 of 7 benchmarks
MiniMax M3.1 Flash
$0.22 / task
Wins 0 of 7 benchmarks
Different efforts: medium · thinking
Terminal-Bench 4.0 Terminal-Bench 4.0 · source setting 2: Agents use a terminal to complete executable coding, system administration and research tasks in the 4.0 suite
Opus 5.552.5
MiniMax M3.1 Flash25.8
FrontierCode 1.1 FrontierCode 1.1: Agents implement changes in real repositories, graded against maintainer-defined requirements
Opus 5.557.1
MiniMax M3.1 Flash38.6
WebDev Arena WebDev Arena: Human pairwise preferences in the stated webdev vote pool
Opus 5.5 · max1,807
MiniMax M3.1 Flash1,587
SciCode SciCode: Writing code for real scientific computing problems (physics, biology, math)
Opus 5.559.3
MiniMax M3.1 Flash53.4
DeepSWE 1.1 DeepSWE 1.1: Agents change repository code to resolve software engineering tasks under the stated DeepSWE edition
Opus 5.5 · max72.3
MiniMax M3.1 Flash—
Terminal-Bench Science 0.1 Terminal-Bench Science 0.1: Agents complete expert-authored research workflows across five scientific domains in a terminal
Opus 5.543.3
MiniMax M3.1 Flash—
MirrorCode MirrorCode: Agents reimplement software projects by observing their behavior
Opus 5.5 · max77.4
MiniMax M3.1 Flash—

Specs

SpecOpus 5.5MiniMax M3.1 Flash
Input, per 1M$4$0.15
Output, per 1M$20$0.60
Cost per task?$1.34$0.22
Speed, tok/s81105
Context1M1M
WeightsClosedClosed
ReleasedSep 2026Oct 2026
See images✓✓
Read PDFs✓—
Hear audio——
Watch video—✓
Call tools✓Partial
Force a tool call—?
Return strict JSON✓Partial
Search the web✓?
Run code✓?
Use a computer✓?

What breaks when you switch

Opus 5.5 → MiniMax M3.1 Flash
No PDF input
Complete model response must be appended›

In multi-turn tools, preserve the complete assistant response, including reasoning_content and tool_calls, to maintain reasoning continuity.

MiniMax M3.1 Flash → Opus 5.5
No forced tool use›

Forced tool_choice any or tool returns HTTP 400; remove the forced choice.

Thinking is always on›

Disabled thinking or a manual budget returns HTTP 400; omit thinking or use adaptive thinking.

Remove sampling parameters›

Non-default temperature, top_p or top_k returns HTTP 400; omit these parameters and use prompting.

No assistant prefill›

Assistant prefill returns HTTP 400; use structured outputs or system instructions, with system instructions on Bedrock.

Old computer tool rejected · Claude API / Google Cloud›

The computer_20251124 tool returns HTTP 400 on the Claude API and Google Cloud; use computer_toolset_20260801 there.

Return thinking blocks unmodified›

Edited, reordered or partially dropped thinking blocks return HTTP 400; echo assistant messages complete and unmodified with tool results.